JP2927073B2 - Thermal transfer recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording apparatus in which an ink film and an image receiving paper are transported between a platen and a print head, and the ink film is irradiated with a laser beam to transfer the ink to the image receiving paper. .

[0002]

2. Description of the Related Art As Lee Nkufi <br/> Lum for use in a thermal transfer recording apparatus, and melt type film to be heated to melt ink of the ink film by the print head is adhered to the image receiving paper, an ink film ink by the print head Sublimation film which is sublimated and adhered to an image receiving paper. As the sublimation type ink film, there is an ink film of a type in which the ink is sublimated by irradiating the ink film with a laser beam (Japanese Patent Application Laid-Open No. Hei 2-2).
02488). In the ink film disclosed in this publication, a spacer beam is included in one of the ink films to prevent the ink film from adhering to the image receiving paper.

[0003]

In a conventional thermal transfer recording apparatus using a thermal sublimation type ink film, a large pressure is applied to the image receiving paper and the ink film by the print head and the platen against the image receiving paper and the ink film. ing. However, in a conventional thermal transfer recording apparatus using a sublimation type ink film, even when using a type of ink film in which ink is sublimated using a laser beam, about a Since there are irregularities of about 2 μm, a white spot phenomenon called a void may occur. This void occurs because the ink of the dye layer is efficiently dyed on the convex portion of the image receiving paper, whereas the concave portion has a gap between the ink film and the dye layer. It is considered that this is because the transfer efficiency is low. Further, since the dye layer of the ink film contains a binder and the like other than the dye, these may be transferred to the recording paper as impurities, which causes image unevenness. Therefore, in a thermal transfer recording apparatus mainly using a sublimation type ink film, the occurrence of voids is prevented, and the occurrence of transfer unevenness due to the transfer of impurities is prevented, so that a high-quality image can be formed on an image receiving paper. Being reproducible is a technical problem to be solved today.

Further, if the light energy of the laser beam applied to the ink film for sublimating the ink can be reduced, the transfer efficiency can be improved accordingly. The research was conducted. As a result of research, conventionally, the ink film was transported along the transport guide surface of the print head in contact with it, so the thermal energy generated by irradiating the ink film and converting it to heat was absorbed by the print head Turned out to be.
Conventionally, it has been necessary to irradiate a laser beam having an intensity including extra energy to be absorbed. Therefore,
An object of the present invention is to improve the thermal transfer efficiency so that a high-quality image can be formed on an image receiving paper with less light energy.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method of irradiating a laser beam onto a sublimation type ink film while holding the ink film and an image receiving paper between a print head and a platen. In the thermal transfer recording apparatus for thermally transferring ink to an image receiving paper, the print head and the platen have a gap between the ink film and the image receiving paper apart from a nip portion that sandwiches the ink film and the image receiving paper. in position, the set the irradiation position with respect to the ink film of the laser beam, apertures in the conveyance guide surface formed in said printhead for guiding conveyance of the ink film
The part is formed on the print head corresponding to the irradiation position, and when the ink film is irradiated with laser light, both surfaces of the ink film do not contact any of the print head and the image receiving paper, A thermal transfer recording apparatus characterized in that the transfer is performed while the ink film is floating in the air.

[0006]

The image receiving paper is conveyed while being nipped by a nip formed by a platen and a print head. Since the irradiation position of the laser light provided on the print head is provided at a position shifted from the nip portion, a gap is formed between the ink film and the image receiving paper at the irradiation position, and the ink film is formed on the image receiving paper. The image is formed in a state where the image is not contacted. Furthermore, at the position where the ink film is irradiated with the laser beam, the ink film is also in non-contact with the print head, and the heat energy photo-thermally converted by the ink film is not transmitted from the ink film to the outside, and the heat energy is reduced. The ink is efficiently transferred to the image receiving paper with energy.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments of the present invention. 1 to 3 are views showing a thermal transfer recording apparatus according to one embodiment of the present invention. As shown in FIG. 2, the thermal transfer recording apparatus includes two support plates 11 and 12 which are arranged at a predetermined interval from each other. Has a platen roller 13 rotatably mounted via a bearing (not shown). The platen roller 13 is driven by a motor (not shown), and as shown in FIG.
a and a rubber material layer 13b provided on the outer periphery of the
The center of rotation is indicated by symbol O. The thickness of the rubber layer 13b is about 1 mm, and a rubber material having a hardness of 60 degrees or more in accordance with Asker standard is used so that the roundness of the platen roller 13 is increased. A print head 14 made of a glass plate is disposed adjacent to the platen roller 13, and the print head 14 is located above the platen roller 13 in the illustrated case.

On the lower surface of the print head 14, that is, the surface facing the platen roller 13, an ink film 18 which is fed from a supply roll 16 and wound on a take-up roll 17 is guided and moved. The ink film 18 includes a rubber pinch roll 21.
It is driven by a capstan roller 22 pressing the ink via the ink film 18 and moves in a direction indicated by an arrow A in FIG. These rollers 21, 22 are located between the take-up roll 17 and the print head 14. Also, the print head 14 and the supply roll 16
And a metal tension roller 23 and a rubber tension roller 24 pressed against the metal tension roller 23 via the ink film 18.
A sliding clutch (not shown) is built in the ink film 24, and a braking force for applying a tension to the ink film 18 is applied to the ink film 18.

The image receiving paper 25 is guided by the platen roller 13 in contact with a substantially semicircular portion facing the print head 14. The rotation of the platen roller 13 causes the image receiving paper 25 to synchronize with the movement of the ink film 18. Transported. Rotation center O of platen roller 13
On the other hand, the two paper pressing rollers 26 and 27 press the platen roller 13 via the image receiving paper, that is, the image forming paper 25, with a phase of about 180 °. The direction of conveyance of the image receiving paper 25 accompanying the rotation of the platen roller 13 is indicated by an arrow B.

The lower surface of the print head 14, that is, the conveyance guide surface for guiding the conveyance of the ink film 18 in opposition to the platen roller 13, as shown in FIG.
3 and slightly curved. Thereby, when tension is applied to the ink film 18,
Wrinkles do not occur, and the ink film 18 adheres well to the conveyance guide surface of the print head. Platen roller 1
When the print head 3 and the print head 14 are brought into contact with each other as shown in FIG. 1, a nip portion N is formed. The width of the nip N is set to about 1 mm. The ink film 18 is guided and conveyed by the conveyance guide surface of the print head 14, and the image receiving paper 25 is conveyed while being guided by the arc-shaped opposing surface. And comes into contact with each other at the nip portion N, and then separates from each other past this portion.

As shown in FIG. 1, a transfer portion, that is, an irradiation position P is provided at a position shifted by a stroke X from the center of the nip portion N to the downstream side in the transport direction of the ink film 18 and the image receiving paper 25. I have. This irradiation position P is
The laser beam L having a wavelength of 810 nm is set so as to be focused by the optical system 28 on the photothermal conversion layer of the ink film 18. The laser light source is a high-power semiconductor laser, for example, SLD304X manufactured by Sony Corporation.
Use T. An anti-reflection treatment is applied to the surface of the print head 14 by applying a metal vapor-deposited film or the like so that the laser beam L having the above wavelength is less reflected on the surface of the glass print head 14. On the other hand, the platen roller 13 is desirably raised to a predetermined temperature in order to increase the dye receiving efficiency of the image receiving paper, that is, the image density.

As described above, the irradiation position P of the laser beam
Is provided at a position displaced from the center of the nip portion N, an air gap having a dimension Y is formed between the ink film 18 and the image receiving paper 25 at this position. Is transferred in a non-contact state. The value of the air gap Y is adjusted by the distance X between the rotation center O of the platen roller 13 and the optical axis of the laser beam L, that is, the irradiation position P. In the case shown, the value Y can be adjusted in the range of 0 <Y <200 μm. To form a high quality image on the image receiving paper 25, the value Y is adjusted to 5 <Y <50 μm.
It is preferable to set it in the range of m.

As shown in FIG. 1, a print head 1
4, a light-transmitting concave portion 31 that opens to the transport guide surface is formed corresponding to the irradiation position P. As shown in FIGS. 1 and 2, the recess 31 is formed by providing a groove parallel to the rotation center O of the platen 13 over the entire length of the print head 14. Therefore, when the ink film 18 is irradiated with the laser beam, the front and back surfaces of the ink film 18 do not come into contact with either the print head 14 or the image receiving paper 25, and the ink film 1
The transfer is performed in a state where 8 is floating in the air. This allows
The heat energy photo-thermally converted in the small-capacity ink film 18 is not absorbed by the large-capacity glass print head 14 that maintains almost room temperature.
It is consumed as energy for efficiently sublimating the ink. The formation of the groove or recess 31 in this manner not only improves the thermal efficiency but also contributes to an increase in printing speed, and also prevents the ink film 18 from being in frictional contact with the laser light transmitting portion. It also serves to prevent a decrease in the amount of transmitted light due to scratches and adhesion of impurities.

At the edge of the opening of the light-transmitting recess 31,
As shown in FIG. 1, an arc-shaped R portion 32 is formed. The R portion 32 prevents the back surface of the ink film 18 from being scratched and prevents the impurities attached to the ink film 18 from accumulating in the recess 31.

FIG. 4 is a diagram showing a configuration of the ink film 18 and the image receiving paper 25.
On the base film 18a formed of polyethylene terephthalate or the like and absorbing little at the wavelength of the laser light L, a light-to-heat conversion layer 18b of high absorption formed of, for example, carbon, and a color in which a dye is dispersed in a polymer binder. The agent layer 18c is applied. On the other hand, the image receiving paper 25
For example, an image receiving layer 25b for receiving a dye such as polycarbonate or polyurethane is coated on a base material 25a such as polyester or condenser paper.

When the laser beam L is focused on the photothermal conversion layer 18b of the ink film 18, the photothermal conversion agent generates heat,
The heat is transmitted to the colorant layer 18c. When the sublimable dye is excited by heat in the colorant layer, the solid that had been in the polymer binder as a solid is vaporized and jumps out. At that time,
If the image receiving layer 25b is located very close to the image receiving layer 25b, the sublimable dye that has jumped out is trapped by the image receiving agent.
b is dyed. After dyeing, the image receiving layer 25b is preferably cooled once to a room temperature level. This is for strengthening the bond between the dye and the image receiving agent so that the dye does not sublimate again when it is heated again. This is, in particular,
In a color printer by superimposing three or four colors, when dyeing the next color, the image receiving paper 25 is exposed again to heat, which is important for maintaining color balance.

Next, referring to FIG.
The procedure for adjusting the distance X between the center O and the optical axis and the width Y of the air gap will be described. As shown in the drawing, the platen roller 13 and the print head 14 are pressed against each other, and the rubber material 13b of the platen roller 13 is deformed by pressing, so that a nip portion N having a certain width is formed. However, in FIG. 2, the ink film 18 and the image receiving paper 25 conveyed while being sandwiched between the platen roller 13 and the print head 14 are not shown. Therefore, in FIG. 2, it is assumed that the image receiving paper 25 is wound. Two support plates 1
A photosensor H for detecting a laser beam L is attached to each of the laser beams 1 and 12, and the laser beam L is scanned in the direction of the main scanning line S at the position of the sensor H. The mounting position of the sensor H is adjusted to be a distance Z with respect to the rotation center O of the platen roller 13. The width Y of the air gap is the platen roller 1
3 is determined by the distance Z between the rotation center O and the main scanning line S. When the main scanning line S is located in the nip portion N,
Since the width Y of the air gap becomes O, the value of Z is always larger than 1/2 of the width of the nip portion N.

The adjustment of the position of the main scanning line is performed by adjusting the optical system. At this time, the main scanning line S of the laser beam L to be scanned passes through the center of the left and right photosensors H. The photosensor H is set so that the output voltage becomes maximum when the laser beam L crosses the center of the photosensor by means such as providing a slit on the photodetector. In this way, if both the left and right photosensors H are adjusted to have the maximum output, the positional relationship between the photosensors H and the center O of the platen roller 13 has already been adjusted. The laser beam L scans the Y position.

Referring to FIG. 3, the relationship between the above-mentioned values X and Y will be described. The radius of the platen roller 13 including the image receiving paper 25 in a state where the image receiving paper 25 is wound is R, and the nip N Reference line M orthogonal to the line connecting the center O
And a distance between the reference line M and the intersection of the surface of the image receiving paper 25 is b, the value of Y is Y = ab. Then, since a = R, b
Is determined by the following equation. b = (R ² −X ² ) ^{1/2 In} this manner, the value of the air gap Y is obtained. In practice, however, the size is obtained by subtracting the dent of the rubber layer 13 b of the platen roller 13.

FIGS. 5 and 6 are views showing a thermal transfer recording apparatus according to another embodiment of the present invention, wherein members common to those in the above embodiment are given the same reference numerals. In the case shown in FIG. 5, the light transmitting concave portion 31 is formed by forming a step portion on the downstream side of the ink film 18 from the irradiation position P of the print head 14. Forming the steps in this way makes it easier to process the recesses 31 than forming grooves as shown in FIG.

In the print head 14 shown in FIG. 6, a light-transmitting concave portion 31 is formed by forming a groove formed by connecting arc surfaces including the R portion 32. As described above, the shape of the concave portion 31 may be various as long as the portion of the ink film 18 irradiated with the laser beam L does not contact not only the image receiving paper 25 but also the conveyance guide surface of the print head 14. It is possible to set the shape. Further, as the shape of the print head 14, the radius of curvature may be reduced to such an extent that the conveyance guide surface becomes a semicircular shape, or the conveyance guide surface may be flat.

As described above, since the transfer portion P, that is, the portion irradiated with the laser beam L is set at a position shifted from the nip portion N, the ink film 18 guided by the print head 14 and the image receiving guide guided by the platen 13 An image is formed at a position apart from the paper 25. Thereby, the color material layer 18c of the ink film 18 and the image receiving paper 25
The dye is transferred in a state where the surfaces are not in contact with each other. Therefore, impurities other than the dye were not transferred to the image receiving paper, the occurrence of image unevenness was prevented, and a high-quality beautiful image was reproduced. Also, the image receiving paper 25
As a result, the size of the unevenness of the surface is relatively smaller than the size of the air gap Y, so that it is not directly affected by the unevenness. It has become possible to reproduce a high-quality image from the viewpoint of eliminating the phenomenon described above.

Further, from the ink film 18 to the image receiving paper 25
In addition to the heat not escaping, the ink film 18 is suspended in the air because the light transmitting recess 31 is formed in the print head 14, so that heat energy does not escape outside the ink film, and the thermal transfer efficiency of the dye is reduced. Improved. Further, with the improvement of the thermal transfer efficiency, the printing speed can be reduced. Then, at a position P of the ink film 18 where the laser light is irradiated,
Since the Priton head 14 does not come into contact, it is possible to maintain a clean state as an optical member for a long period of time, and it is possible to suppress the secular change of the transmitted light amount as much as possible. Since the R portion 32 is formed at the opening edge of the concave portion 31, the coating material and impurities on the back surface of the ink film 18 are prevented from being scraped off and accumulated in the concave portion 31, thereby reducing the amount of transmitted light. Not only can be prevented, but also the maintenance cycle such as cleaning of the print head 14 can be lengthened.

Since the ink film 18 contains a heating element, heat can be efficiently transmitted to the sublimation dye without applying a large pressure between the print head and the platen. And the device can be made lighter and more compact. Also,
Unlike the case where a thermal head is used, the thickness of the base of the ink film is not related to the thermal efficiency. Therefore, the thickness can be increased, so that the manufacture of the apparatus and the handling of the ink film in the apparatus are facilitated.

Instead of the platen roller 13 of the above-described embodiment, a platen having a flat opposed surface can be used. In the illustrated embodiment, the nip portion N
In contrast, the irradiation position P is provided on the downstream side in the transport direction between the image receiving paper 25 and the ink film 18, but the irradiation position P may be provided on the upstream side in the transport direction. Print head 1 corresponding to the irradiation position
4, a concave portion 31 including a groove and a step is formed on the upstream side of the nip portion N.

[0026]

As described above, according to the present invention, the print head or the like does not contact the front and back surfaces of the ink film, and the ink is transferred to the image receiving paper while the ink film is floating. As a result, thermal energy could not escape to the outside of the ink film, and the thermal transfer efficiency of the ink was greatly improved. In addition, since impurities other than the dye are not transferred to the image receiving paper and the occurrence of voids is prevented, a high-quality image can be reproduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a thermal transfer recording apparatus according to one embodiment of the present invention;

FIG. 2 is a plan view of FIG. 1 in a state where an ink film and the like are omitted,

FIG. 3 is an explanatory diagram showing a relationship between a position of a transfer portion and a gap with respect to a center of a nip portion in the thermal transfer recording device shown in FIGS. 1 and 2;

FIG. 4 is a sectional view showing the structure of the ink film and the image receiving paper;

FIG. 5 is a sectional view showing a thermal transfer recording apparatus according to another embodiment of the present invention,

FIG. 6 is a sectional view showing a thermal transfer recording apparatus according to still another embodiment of the present invention.

[Explanation of symbols]

13: platen roller, 14: print head, 18:
Ink film, 25: image receiving paper, 31: translucent recess, 32
... R part, N ... Nip part, P ... Irradiation position.

Claims (2)

(57) [Claims] 1. A printing apparatus , comprising: a sublimation type ink film and an image receiving paper sandwiched between a print head and a platen to be transported.
In a thermal transfer recording apparatus for thermally transferring ink to image receiving paper by irradiating the ink film with laser light, the print head and the platen separate the ink film and the image receiving paper from a nip portion that sandwiches the ink film and the image receiving paper. a position with a gap between the paper and the set the irradiation position with respect to the ink film of the laser beam, the open mouth to the conveying guide surface formed in said printhead for guiding conveyance of the ink film, said printhead Formed in correspondence with the irradiation position, when the ink film is irradiated with a laser beam, both surfaces of the ink film did not come into contact with any of the print head and the image receiving paper, and the ink film floated in the air Thermal transfer characterized by performing transfer in the state Recording apparatus. 2. A thermal transfer recording apparatus according to claim 1, characterized in that the formation of the edge portion of the front formed in the print head KiHiraki opening arcuately.